BCA Spring Meeting 2003 University of York Tuesday 15 March to Thursday 17 April 2003

"Structures having more than one independent formula unit are interesting because they are unusual; only 8% of the structures in the CSD have Z'>1 and fewer than 1% have Z'>2. In some Z'>1 structures the pseudosymmetry is so strong that the structures are best described as modulated; in others the molecules have such different orientations and/or conformations that an analogy can be made with co-crystals. Because Z'>1 structures are exceptional they can provide new insights into crystal packing. They also present interesting technical problems. As a group these structures are wonderful and informative puzzles that too often remain unpublished. Consideration of Z'>1 structures is timely because anecdotal evidence suggests they are more likely to be recognized when a CCD or image-plate detector are used." Professor Carolyn P. Brock, Department of Chemistry, University of Kentucky.

Detailed Programmme

08:30 Sam Motherwell (CCDC) - Packing Energy Patterns in CSD for Z' = 2

09:00 Ton Spek (Utrecht) - Z' Structures from a Symmetry and Molecular Geometry Viewpoint

10:30 Richard Cooper (Oxford) - Z' > 1: just a nuisance, or something more interesting?